Rateless codes mitigation technique in a turbulent indoor Free Space Optics link

Abstract

Free Space Optics (FSO) links are affected by several impairments and, among them, optical turbulence is the most important factor that can degrade the link quality. Due to the presence of this phenomenon, the signal irradiance detected by the receiver fluctuates, thus causing erasure errors and fading events. In this work, we present an indoor Free Space Optics link, in which several turbulence conditions are generated by using two heating elements. We show that the generated turbulence causes erasure errors and packet losses during the data transmission, and we also compare the statistical distribution of the samples with the theoretical models. Moreover, we demonstrate how the application of the most recent rateless codes, i.e., RaptorQ codes, can strongly improve the link quality. In particular, results show that the Packet Error Rate strongly decreases when employing RaptorQ codes. Finally, we conclude that, by properly setting the encoding/decoding parameters, we can correctly receive the whole transmitted data without any errors.